Color photography



May 30, 1944. R. M. EVANS ETAL COLOR PHOTOGRAPHY Filed Dec. 29, 1941 RALPH/W. EVA/vs BEMJAM/NELUBOsHEZ INVENTORS BY W ATTORNEYS Patented May 30, 1944 Ralph 'M. Evans and Rochester; N. Y.,

assignors to Eastman Kodak Company, Rochester, N. Y., a corporation oi New Jersey Application December 29, 1941, Serial No. 424,794 4 Claims. (Cl. 95-14) This invention relates to color photography and particularly to methods and means for labeling color prints.

In certain processes of making color prints from color negatives or transparent positives the processing includes flash exposures of the blue and green-sensitive layers from the front and a flash exposure of the bottom and red-sensitive layer through the support. It has been found that any number printed on the back of the prints masks the red-sensitive layer during this flash exposure and causes the numbers tobe re-, produced in the cyan layer, i. e. the red-sensitive ayer.

It is the object of the present invention to provide a method and means for marking the backs of prints so that the number will not show in the picture'itself.

Of course, whatever ink is used for labeling the prints should be such that it may be easily applied to the back of the paper at the time the first exposure is made or immediately thereafter. Therefore, the ink should be a quick-drying ink and after it has dried, it should be compatible with the processing solutions and with the photosensitive layer .in case the back 01' one print comes in contact with the front or another. Also, the ink should not be removed or removable by the processing solutions. These properties 01' the ink are all necessary ones ii the color process is not to be spoiled in any way.

According to the invention an ink is selected which is completely transparent to red light, at least prior to the immersion in the solutions employed in the process after the red flashexposure. The backs of the prints are labeled with this ink effectively at the time the first exposure is made and the ink pleted;

There are three possible species of this invention. of these the most preierable'one is a dye completely transparent to red light, yet having a fairly high white light density, specifically a magenta dye dissolved in Cellusolve. This solvent is ethoxyethanol or ethylene glycol -monoethyl ether. It is selected because it is quick drying, and when dryis not removed by the'proc cssing solutions, does not lutic-ns, emulsions, and does not aflect the rubber or artificial rubber used in the making of numbering stamps with which the ink is'applid. .It is, of

ail'ect the processing socourse, a solvent for the magenta dye used, which may be any of the magenta dyes employed in color photographic processes.

is visible after the process is comis compatiblewith the photosensitive 7 A second species 0! the invention employs an ink consisting of a slow, red-sensitive emulsion which is not exposed by the first exposure of the print, but is exposed by the red flashing exposure and, hence, develops up in subsequent processing solutions to give satisfactory as the magenta dye in the Cellusolve, because the intensity of the. label depends upon the intensity of the red flash exposure and because it is not as easy to apply.

A third species consists of using an invisible ink, which is rendered visible by immersion in an additional solution after the completion of the color process itself. For example, the invisible ink may be a starch and the prints may be imlnersed in a dilute solution 01' iodine to bring out the characteristic color. The disadvantage of this specie is, of course, the need for an addi tional processing solution.

{The invention will be fully understood when the following description is read in connection with the accompanying drawing in which:

Fig. 1 shows a color printing process in which the invention has been applied. I

Fig. 2 shows the back or a color print carrying a serial number applied according to the present invention.

In Fig. 1', light from a source ll illuminate a colortransparency H and projects an image or it by means of a lens I2 onto a color-sensitive layer It unwound from a supply roll I. At the time this exposure is made, or immediately before or immediately thereafter, an identifying mark such as a serial number is placed on the back or the print. In the example shown, the layer It is advanced to the next exposure position before the serial number is applied by a rubber stamp 52 while the front of the print is held against a support 53. According to the -invention this print is marked with an ink which is completely transparent to red light. Alter exposure, the colorfilm I3. is moved as indicated'by the oken line It to the processing solutions. The broken line I! may include winding up of the fllm l3 and unwinding into the processing solutions as indicated by the portion I! of the fllm. The various parts or the process are only indicated schematically, but they include flashing of the photosensitive layer from the front by means of light from a source I! through a filter 2|, striking the 111m II. The film isthen immersed in further processing solutions as indicated at 26, and the broken lines I1 and 25 may include other immersions in solu a visible image. This is not as film as shown at 28 is exposed to a flash exposure from a light source 30 through a red filter 29 and through the support for the sensitive layer on the film 28. .According to the invention, the ink for labeling the number on the back of the print is such that this flash exposure is not afiected in any way by the presence of the ink. Subsequent steps in the process are indicated at 3|, 3!, and 33. tool 36 and 31 so that a pile 38 of prints are provided on a table 39. According to the invention,

. the ink applied by stamp 52 is such that it is plainly visible on the back of each print in the pile 38.

If, after the number is applied by the stamp 52, the film is wound up before processing, the ink comes in contact with the surface of the 1 sensitive emulsion. Similarly in the final, completely processed prints 38 the number is in contact with the surface of the color print. Thereiore, the ink should be such that it is compatible with the color layers both before and after processing. z

In Fig. 2 the back 50- of a color print is shown having the number 5i printed thereon at one end of the print. 1

Various forms of printing stamps are satisfactory, but we prefer to use one of the type having an automatic .closing inking chamber so that thedquick-drying ink will not be exposed until use Havingthus described our invention, we wish to point out that it is notlimited to this method and Afterwards the film 35 is cut by a suitable particular apparatus, but has the scope of the appended claims. I

What we claim and desire to secure by Letters Patent oi the United States is:

1. In a process of printing from a multicolored record, which process includes exposing a colorsensitive'layer on a support and immersing the layer in solutions, flashing the layer with red light through the support and immersing it in subsequent solutions, the method of labeling prints which comprises marking on the back of each exposed area at effectively the same time as said exposing with a quick-drying ink which, when dry, is not removed by any of the said solutions, is compatible with said sensitive layer, and at least prior to said immersing in subsequent solutions is completely transparent to red light.

2. A method according marking is'done with a magenta dye incellusolve.

3. A method according to claim 1 in which the marking is done with a slow, red-photosensitive, transparent ink which, when exposed to red light, is rendered developable in said subsequent solutions to form a visible material.

4. A method according to claim 1 in which the marking is done with a starch solution and the back of the prints are brought into contact with a dilute solution of iodine after said immersion in subsequent solutions.

RALPH M. EVANS; BENJAMIN E. LUBOSHEZ.

to claim 1, in which the 

